Major OEM's for percussion air equipment, such as rock drills, jackhammers and drifters, have published specification requirements for the fluid that should be used in their equipment. One property that the specification requires the lubricant to meet is to be able to lubricate under extreme pressure, or “EP” conditions. The EP properties of the lubricant are defined by the Timken (ASTM D2782) and Falex EP (ASTM D2670) test standards. EP performance is usually increased by increasing the amount of sulfur (inactive and active) as well as phosphorous compounds in the formulation. Friction modifiers might also be used to change the boundary lubrication properties.
Percussion lubricants must demonstrate the characteristics of long equipment life, reliability in wet conditions, protection in wet environments and low inventory cost. Extreme pressure performance withstands heavy shock loads typical of rock drill service, protecting the equipment against rapid wear. The rock drill piston, rifle bar and nut are thus protected. The lubricant clings to lubricated parts and resists being washed away by trace water in the compressed air. Antirust performance protects critical parts from the corrosive action of wet environments. The lubricant should be multi-purpose, useful in hand oiling and for chain drives, minimizing the number of lubricants in the inventory. This lubricant is effective in lubrication of enclosed gears, industrial plain and anti-friction bearings. It demonstrates low odor and low toxicity.
As a general rule, friction modifiers hurt the performance of anti-wear and/or extreme pressure additives. Generally, the anti-wear or extreme pressure additives in lubricants reduce damage by maintaining a layer of lubricant between the moving parts of the equipment. The additives of the lubricant which provide anti-wear or extreme pressure help reduce harmful metal on metal contact. There is a need for lubricants for rock drills which provide a balance between frictional properties and anti-wear/extreme pressure properties. The lubricant of the current application possesses such a synergistic balance.